An object’s velocity describes the object’s speed and direction of motion.

Section 2: Velocity and Momentum

KWhat I Know

WWhat I Want to Find Out

LWhat I Learned

• 4(A) Describe and calculate an object’s motion in terms of position, displacement, speed, and acceleration.

Velocity and MomentumCopyright © McGraw-Hill Education

Essential Questions• What is the difference between speed and velocity?

• How is the motion of two objects relative to each other described?

• How can an object’s momentum be calculated?

Velocity and MomentumCopyright © McGraw-Hill Education

Review• speed

New• velocity• momentum

Velocity and MomentumCopyright © McGraw-Hill Education

Vocabulary

Velocity Speed describes only how fast something is moving.

To determine direction you need to know the velocity.

Velocity includes the speed of an object and the direction of its motion.

Velocity and Momentum Copyright © McGraw-Hill Education

Relative Motion

If you are sitting in a chair reading this sentence, you are moving.

You are not moving relative to your desk or your school building, but you are moving relative to the other planets in the solar system and the Sun.

Velocity and Momentum Copyright © McGraw-Hill Education

MomentumA moving object has a property called momentum that is related to how much force is needed to change its motion

The momentum of an object is the product of its mass and velocity.

Velocity and Momentum Copyright © McGraw-Hill Education

MomentumMomentum is given the symbol p and can be calculated with the following equation:

Velocity and Momentum Copyright © McGraw-Hill Education

The unit for momentum is kg · m/s. Notice that momentum has a direction because velocity has a direction.

MomentumWhat is the momentum of a car with a mass of 1,300 kg traveling north at a speed of 28 m/s?

Identify the Unknown:

Velocity and Momentum Copyright © McGraw-Hill Education

momentum: p

List the Knowns: mass: m =velocity: v =

1,300 kg

28 m/e north

Solve the Problem:

Set up the Problem: p = mv = (1,300 kg) x (28 m/s) north

p = (1,300 kg) x (28 m/s) north

= 36,400 kg x m/s north

MomentumWhen two objects have the same velocity, the object with the larger mass has the larger momentum.

Velocity and Momentum Copyright © McGraw-Hill Education

For example, a 1,500-kg car traveling at 30 m/s east has a momentum of 45,000 kg • m/s east.

Animation

Concepts in Motion

FPOAdd link to concepts in motion animation from page 49 here.

Velocity and Momentum Copyright © McGraw-Hill Education

Velocity and Momentum Copyright © McGraw-Hill Education

Review

Essential Questions• What is the difference between speed and velocity?

• How is the motion of two objects relative to each other described?

• How can an object’s momentum be calculated?

Vocabulary• velocity• momentum